Changelog doesn't talk about anything new for GPS firmware except version bump. Maybe, GPS was in a good day in your area. For me I already don't complain about its accuracy, but another one may complain for the same...
Given that the GPS firmware hasn't changed at all (it was 4.80 and is not 5.00 but as they mention in the changelog, the only difference is the version number to bring it line with other models) then I expect any "GPS is better/worse" is down to weather/buildings/location/GPS constellation overhead than anything else.
My GPS tracking is the same as it's always been, good enough for me to get fitter with. Is it metre perfect? No.
This is like that other person who posted how much worse WHR has become in 15.20. Well again, the sensor FW didn't change at all, so something else is going on.
